1. Field of Invention
The present invention is directed to a process for treating a thin stillage portion of a by-product of a process for producing alcohol, and to products of the process. The invention is also directed to a process for treating a yeast-containing portion of a by-product of beer production. More particularly, the invention relates to the production of flavoring compositions from the thin stillage portion produced during alcoholic beverage distillation, and from the yeast-containing portion of a by-product of beer production.
2. Related Art
It is known that the fermentation of various carbohydrate materials, such as cereal grains, and subsequent distillative separation of volatile products, such as ethanol, provides distillation residues. These residues have been the subject of attempts by researchers to manufacture a food or food supplement which takes advantage of their nutritional attributes. In particular, the spent mash, which includes distillers' grains and solubles, is believed to have considerable nutritional value due to its high protein and fiber content and has been shown to be useful as a supplement for ruminant animal feed. For example, Baeling et al., U.S. Pat. No. 4,552,775, discloses a method of thermally dewatering the liquid stillage residue from the fermentation and distillation of grain raw material to produce an animal feed.
It is also known to produce a human quality food from some by-products of fermentation and distillation of grain raw materials. For example, Rasco et al., U.S. Pat. No. 4,828,846, discloses a food product suitable for human consumption produced from cereal grain residues remaining after alcohol fermentation. The food product is suitable for use as a supplement to baking flours and the like. This product is obtained by controlling between 4.0-5.0 the pH of various enzymatic conversions of starch. The pH is controlled using citric, malic, acetic, lactic, tartaric, fumaric, succinic, nitric or hydrochloric acids. The pH of the slurry residues remaining after the distillation is adjusted to between 5.0 and 8.0 using hydroxides of sodium, potassium or calcium, and the product is dried at a temperature of less than 170.degree. F. Rasco discloses that adjusting the pH of the slurry to below 5.0 results in a product which will be rejected as "too sour," and adjusting the pH of the slurry to above about 8.0 results in a product which will be rejected as "too alkaline" (Rasco, column 4, lines 24-28).
In Thacker et al., U.S. Pat. No. 5,061,497, a method of coproduction of ethanol and a high protein, high fiber food product is disclosed which involves suspending grain in a slurry and liquefying the starch therein. The liquefied starch is separated from the grain solids fraction, and the grain solids fraction is prepared into a solids cake. None of the prospective food product undergoes the fermentation process.
These attempts, however, have not been altogether successful. Many food products made according to these processes have failed to eliminate the bitter taste of the solubles in the spent mash and acquired their unpleasant taste. See for example, Bookwalter et al., "Investigations On The Use Of Distillers' Grains or Fractions Thereof In Blended Foods For The Foods For Peace Program And Other Food Applications," U.S. Dept. of Agriculture Final Report, August 1, 1981-August 31, 1983.
It is also known to produce a flavoring for food from starch-free cereal grains. For example, Sfat, U.S. Pat. No. 3,689,277, discloses a caramel flavoring and a method of preparation of same from a starch-free protein hydrolysate by heating a granular intimate mixture of a protein hydrolysate and a sugar at between 75.degree.-100.degree. C. until a caramel flavor is imparted to the mixture. Rusoff, U.S. Pat. No. 2,887,388, discloses the production of a chocolate base flavor by reacting partially hydrolyzed proteins with reducing sugars and precursors thereof at a temperature which is dependent on the specific saccharide used.
The above patents and publications disclose advances made in the art of preparing food products from the by-products of distillation processes, and also in the preparation of flavorings from starch-free cereal grains. None of these patents or publications, however, discloses or suggests a method of preparing a flavoring composition only from the solubles or thin stillage portion of the spent mash produced in a distillation process, without modifying the fermentation process. Also, none of these patents or publications discloses or suggests the use of only the solubles or thin stillage portion of the spent mash, allowing the wet distillers' grains to be used for purposes for which they are well suited, e.g., in ruminant animal feed. Moreover, the prior art discussed above does not disclose or suggest a method of preparing a flavoring whose flavor can be changed by changing specific steps in the process.